The Touring Store claims the Ortlieb XL rack pack is a better choice than the Bob version (https://www.thetouringstore.com/ORTLI...ACK%20PAGE.htm). Any comments on this claim? Interested in photos too - I couldn't find any.

they claim a higher level of waterproofing and durability for the ortlieb bag. i don't know how they make that claim, but i suppose it could be a better choice if it is true. i have never had any waterproofing or durability issues with my bob bag, but one of the handle straps is starting to delaminate slightly. i have had and used it for 7 years, and i think i will get many more years from it, so i wouldn't say the bob bag is exactly bad. from the pictures, they both smell the same to me and i think that store is trying to make a sale.

There is no question that the Bob bag fits the Bob trailer perfectly so that's my default choice.

I have been using the same Ortlieb XL rack pack for 12 years on the tandem when extra capacity is needed. I use it even more for kayak touring. It has been very durable and of course very waterproof.
I think that their claim could well be valid after seeing and handling the BOB bag.

I have used Patagonia's dry bags for years canoeing and rafting. In 2007 my son and I put together a self guided arctic river rafting trip for 10 days. I used bags that were 10 years old (Black Hole model).
Neither river water nor rain penetrated these bags. Everything stayed dry in these bags. They'd probably work well in a Bob too. BTW I always double bag whatever brand name I use on wilderness trips.

I thought about getting one of the XLs too.

If you believe the specs, its larger volume and lower weight than the Yak bag.

https://www.biketrailershop.com/catal...289-p-104.html

here's another idea

https://www.ortliebusa.com/CartGenie/prod-23.htm

Thanks for the links. The drysack/backpack looks nice but maybe a bit small for someone not carrying panniers.

I found a page with a photo of the Ortlieb XL rack pack in a Bob Yak here.